Image of a mouse brain that received a direct transplantation of hematopoietic stem cells. The image reveals the transplanted cells (green) rapidly engrafted and gave rise to new cells (also green) that have widely distributed throughout the entire brain.

A therapeutic technique to transplant blood-forming (hematopoietic) stem cells directly into the brain could herald a revolution in our approach to treating central nervous system diseases and neurodegenerative disorders.

The technique, which could be used to transplant donor-matched hematopoietic stem cells (HSCs) or a patient’s own genetically-engineered HSCs into the brain, was reported in Science Advances today by researchers from the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and the San Raffaele Telethon Institute for Gene Therapy.

In their study, the team tested the technique in a mouse model to treat lysosomal storage disorders, a group of severe metabolic disorders that affect the central nervous system.

The team’s findings are groundbreaking because, until now, it was thought that HSCs — from a healthy, matched donor or a patient’s own genetically-corrected cells — needed to be transplanted indirectly …

David Williams, MD, the principal investigator of the clinical trial, discusses gene therapy and its impact on children with adrenoleukodystrophy

Adrenoleukodystrophy — depicted in the 1992 movie “Lorenzo’s Oil” — is a genetic disease that most severely affects boys. Caused by a defective gene on the X chromosome, it triggers a build-up of fatty acids that damage the protective myelin sheaths of the brain’s neurons, leading to cognitive and motor impairment. The most devastating form of the disease is cerebral adrenoleukodystrophy (CALD), marked by loss of myelin and brain inflammation. Without treatment, CALD ultimately leads to a vegetative state, typically claiming boys’ lives within 10 years of diagnosis.

Mitochondria, as you may know, are the engines that power cells. They’re always in motion, supplying energy wherever it’s needed. In brain cells, mitochondria especially have to hoof it around, traveling out into the axons and dendrites to fuel the energy-intensive task of communicating with other cells.

But in at least one form of Parkinson’s disease, that movement becomes a problem: the genetic mutations causing the disease leave neurons unable to make the fidgety organelles hold still. Without this ability, the dopamine-producing neurons in the brain’s substantia nigra can’t safely dispose of mitochondria when they go bad, and the neurons die or become impaired.

“When damaged, mitochondria produce reactive oxygen species that are highly destructive, and can fuse with healthy mitochondria and contaminate them, too,” explains Tom Schwarz, of the F.M. Kirby Neurobiology Center at Children’s Hospital Boston, senior investigator on a study published in Cell today. “It’s the equivalent of an environmental disaster in the cell.” …